Atmospheric super-rotation

Atmospheric superrotation is circulation whose axial angular momentum per unit mass exceeds that of the underlying body's equator. An eastward equatorial jet is a common manifestation, but it requires a continuing source of equatorial momentum convergence rather than merely a local temperature difference.

In models of exoplanets under tidal locking, day-night heating excites large-scale Rossby waves and Kelvin waves. Their phase structure transports eastward momentum toward the equator and can maintain the jet against drag. This mechanism was demonstrated using an analytic model and numerical calculations of increasing complexity.^[ref] Such a jet can shift a bright atmospheric region eastward, affecting an exoplanet thermal phase curve, although a brightness offset alone does not uniquely measure a wind speed.